The Good Earth

Australian Geographic | November 2019

Wilderness soil in Mount Lofty (Randy Larcombe)

The more diverse the microbe community in the soils around us, and the more you are exposed to it, the healthier you become.

by Wilson da Silva

EVEN ON A BLUSTERY winter’s afternoon, Mount Lofty flaunts its splendour as a bushland oasis, one of the last vestiges of the original forests and woodlands that once dotted the Adelaide Plains.

Walking the winding nature trails here, you encounter a multitude of native trees, shrubs, climbing plants, reeds and grasses, two-thirds of which harbour fruit, seeds or insects that attract birds, or nectar that brings butterflies. Meandering down the narrow tracks from the summit, you feel invigorated by the scenery, the silence, the smell of wet earth after a light shower. To a city dweller, the air itself seems therapeutic.

And it’s not an illusion. Every time you enter wild spaces replete with biodiversity and breathe the air, microbes wafting through the ecosystem land on your skin, enter your lungs and gut and become part of you. They join the many billions already living in your microbiome – the community of symbiotic micro-organisms inside each human being.

Scientists have long known about these minuscule, mutually beneficial helpers in our bodies. But thanks to technological developments in molecular imaging, computer speed and rapid genetic sequencing, they have in recent years been astounded to realise how crucial and widespread the role played by our microbiome is in everything from nutrition to disease resistance and even mental health.

The latest surprise is the discovery by researchers in Adelaide that the more diverse the microbes living in the soils around us, and the more you are exposed to them, the healthier you become. It’s a discovery that could change our cities, and make us healthier, on a global scale. And it all comes down to humble earth.

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